Pin Docker builds and Netlify previews to Hugo 0.169.0. Replace
deprecated `.Params.summary` lookups with `.RawSummary` in the guide
template.
Validation: the full minified debug build passed with
`--panicOnWarning`, path checks, and unused-template checks, with no
deprecation notices. Dockerfile and template formatting checks, Markdown
post-processing tests, rendered summary/redirect checks, and API output
validation passed.
David Karlsson
47172b3700